Red Giant Members Research Articles

NGC 2423 and the red giants of the Hyades supercluster

view Abstract Citations (17) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS NGC 2423 and the red giants of the Hyades supercluster. Eggen, O. J. Abstract An extensive set of photometric data for members of the cluster NGC 2423 is examined, and the results are compared with those for red giant members of the Hyades supercluster. Intermediate band and RI or H-beta observations for 34 stars of the cluster are listed, and photometric parameters for A and F stars in the cluster are shown. Parameters are also depicted for red giants in the Hyades supercluster, red giants of Hyades abundance, and M type variables in the Hyades supercluster. The intrinsic (b-y), M(1) and (R-I),(b-y) relations for normal giants with Hyades metal abundance are presented. NGC 2423 is shown to be very similar to the Hyades with red giants that match the luminosity and temperature distribution of those in the Hyades. The red giants of the Hyades which are within about 200 pc of the sun are found to have parallel (U,V) motions with the main sequence stars of the Hyades nuclear cluster. Publication: The Astronomical Journal Pub Date: February 1983 DOI: 10.1086/113305 Bibcode: 1983AJ.....88..190E Keywords: Red Giant Stars; Star Clusters; Stellar Spectrophotometry; A Stars; Abundance; F Stars; H Beta Line; M Stars; Main Sequence Stars; Stellar Luminosity; Stellar Motions; Stellar Spectra; Stellar Temperature; Astronomy full text sources ADS | data products SIMBAD (60) GCPD (1)

Evidence from sodium-abundance variations among red giants of M13 for inhomogeneities in the protocluster gas

view Abstract Citations (116) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence from sodium-abundance variations among red giants of M 13 for inhomogeneities in the protocluster gas. Peterson, R. C. Abstract Evidence from high-resolution spectra is presented for star-to-star variations of an order of magnitude in the sodium abundances of red-giant members of the globular cluster M13. It is shown that the large enhancement of the weak 2.10 eV Na I lines at 5682 and 5688 A which is observed in II-67 with respect to II-76 cannot have been misinterpreted because of errors in the model-atmosphere abundance analysis. Except for oxygen (and/or carbon), no other element observed gives evidence for abundance variations from star to star. Since sodium is theoretically difficult to synthesize during giant-branch evolution, the abundance differences must reflect pre-existing variations in the protocluster gas in which the overall metallicity level was preserved. Publication: The Astrophysical Journal Pub Date: May 1980 DOI: 10.1086/157950 Bibcode: 1980ApJ...237L..87P Keywords: Globular Clusters; Interstellar Gas; Protostars; Red Giant Stars; Sodium; Stellar Spectra; Abundance; Inhomogeneity; Line Spectra; Nuclear Fusion; Astrophysics full text sources ADS |

Metal abundance and helium content of the open cluster NGC 7789: Evidence for mass loss

Interstellar reddening, the ratio [Fe/H], effective temperatures, surface gravities, and masses for twelve ‘clump’ stars at the blue end of the giant branch and for seven non-clump red giant members in NGC 7789 have been determined from existingUBV andDDO photoelectric data. For the metal abundance and helium content of the clump stars we foundZ∼0.01 andY∼0.38, respectively. The masses of the red giants are found to be higher than those of the clump stars. On average, the masses of the clump stars are about half of the turnoff point mass. We conclude that the clump stars could have undergone mass loss before reaching their helium core burning phase of evolution. This conclusion arises from an analysis of the several sources entering our mass determination.

BASIC PARAMETERS OF THE OPEN CLUSTER NGC 2571.

ABSTRACT Photoelectric measurements in the UBV system are presented for 49 stars in NGC 2571. The intensity of the Hfi line was measured for the five brightest cluster members and DDO photometric data were obtained for the possible red-giant member CD 2905941. The UBV-H analysis confirms that NGC 2571 is a genuine open cluster, with a minimum membership of 28 stars. The red-giant CD 2905941 is most probably not a cluster member. A uniform E(B- V) = was found for the cluster. A distance of (1.25 j 0.08) kpc, an age of 2.7 x 10 years, and other basic parameters were also derived. Key words: open clusters - UBV-H and DDO photometry

A Method for Determining the Chemical Composition Parameters (X, Y, Z) of Galactic Clusters

A method is described by means of which the chemical composition parameters (X, Y, Z) may be derived for galactic clusters that contain evolved red giant members and for which the cluster reddening and distance moduli are known. The method is based on observations of the evolved stars utilizing the DDO intermediate-band system. First, the DDO photometry by itself allows one to separate with a high degree of certainty the physical members of the clusters from the field stars. In cases where membership in the cluster can be confirmed, the unreddened DDO colours can be used to obtain the effective temperatures, surface gravities and metal abundances (Z) of the stars. These data combined with the absolute magnitudes available from the distance modulus permit the masses to be calculated. Finally, if some of the observed red giants form part of a clump on the giant brach in the HR diagram, the helium abundance (Y) of the clusters can be estimated by comparing the derived physical parameters of these stars with theoretical models. An example of the application of the method to the galactic cluster NGC 2420 is given.

Physical Properties of the Red Giants in NGC 2420

The effective temperatures, surface gravities, and masses of 11 red giant members of the old open cluster NGC 2420 have been derived from existing intermediate-band photometry on the David Dunlap Observatory system. The mean mass of the stars was found to be 0·7 ℳ⊙. The data permit the helium abundance of the cluster to be estimated and result in the value Y = 0·30.

The Galactic Cluster M25.

view Abstract Citations (19) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Galactic Cluster M25. Landolt, Arlo U. Abstract Photometric data on the Johnson-Morgan B, V system are given for 1401 stars in the cluster area. Differential reddening exists across the cluster region and ranges from a minimum value of E(B-v) = 0.29 magnitudes to a maximum of E(B-v) = 0.60 magnitudes. A distance modulus of 9.0 + 0.2 magnitudes was derived through the utilization of the Johnson evolutionary deviation curve method. There appear to be two G-type red-giant members of the cluster in addition to the 6.7-day classical cepheid U Sagittarli. The chister luminosity function was studied to Mv = +5.0 and tends to agree with the Salpeter initial luminosity function. Publication: The Astrophysical Journal Supplement Series Pub Date: February 1964 DOI: 10.1086/190093 Bibcode: 1964ApJS....8..352L full text sources ADS | data products SIMBAD (148)